1. Field of the Invention
The invention relates generally to a power adapter that converts an alternating current (AC) to a direct current (DC). More particularly, the invention provides a power adapter having a freely rotatable DC plug connection that can relieve mechanical stresses produced in the DC wire when it is wound.
2. Description of the Related Art
FIG. 1A is a perspective view showing the connection conventionally achieved between a direct current (DC) wire and a DC terminal of a power adapter. As shown, a traditional power adapter 100 comprises a main body 102, a DC wire 104, and an alternating current (AC) wire 108. The main body 102 further includes a DC terminal 102a and an AC terminal 102b that, respectively, electrically connect the DC wire 104 and the AC wire 108.
Within the traditional power adapter 100, the electrical and mechanical connection between the main body 102 and the DC wire 104 is usually achieved via welding, which therefore fixedly attaches the DC wire 104 to the main body 102. As a result, when the DC wire 104 is wound around the main body 102 for convenient arrangement, the definitive fixation between the DC wire 104 and the DC terminal 102a causes the generation of internal mechanical stresses at their corresponding connecting zone. To attenuate the effects caused by these mechanical stresses, a stress-buffer structure 106 may be provided at the connecting zone between the DC wire 104 and the DC terminal 102a. 
FIG. 1B is a perspective view showing the traditional connection between the AC wire and the AC connector port within a power adapter. As shown, the casing 102 is further provided with an AC connector port 110 that is placed at the AC terminal 102b. The AC wire 108 directly engages by insertion in the AC connector port 110.
At some degree, the stress-buffer structure 106 may attenuate the mechanical stresses produced at the connecting zone between the DC wire 104 and the main body 102 during wire winding. However, this beneficial result is limited because the bending angle of the wound DC wire 104 is excessively high.